java.lang.Object
- org.springframework.cache.support.AbstractValueAdaptingCache

All Implemented Interfaces:
Cache
Direct Known Subclasses:
CaffeineCache, ConcurrentMapCache, JCacheCache
```
public abstract class AbstractValueAdaptingCache
extends Object
implements Cache
```
Common base class for Cache implementations that need to adapt null values (and potentially other such special values) before passing them on to the underlying store.
Transparently replaces given null user values with an internal NullValue.INSTANCE, if configured to support null values (as indicated by isAllowNullValues().
Since:
4.2.2
Author:
Juergen Hoeller

Nested Class Summary
- Nested classes/interfaces inherited from interface org.springframework.cache.Cache
  Cache.ValueRetrievalException, Cache.ValueWrapper

Constructor Summary
Constructors
Modifier Constructor Description
protected AbstractValueAdaptingCache(boolean allowNullValues)
Create an AbstractValueAdaptingCache with the given setting.

Method Summary

All Methods Instance Methods Abstract Methods Concrete Methods
Modifier and Type	Method	Description
`protected Object`	`fromStoreValue(Object storeValue)`	Convert the given value from the internal store to a user value returned from the get method (adapting `null`).
`Cache.ValueWrapper`	`get(Object key)`	Return the value to which this cache maps the specified key.
`<T> T`	`get(Object key, Class<T> type)`	Return the value to which this cache maps the specified key, generically specifying a type that return value will be cast to.
`boolean`	`isAllowNullValues()`	Return whether `null` values are allowed in this cache.
`protected abstract Object`	`lookup(Object key)`	Perform an actual lookup in the underlying store.
`protected Object`	`toStoreValue(Object userValue)`	Convert the given user value, as passed into the put method, to a value in the internal store (adapting `null`).
`protected Cache.ValueWrapper`	`toValueWrapper(Object storeValue)`	Wrap the given store value with a `SimpleValueWrapper`, also going through `fromStoreValue(java.lang.Object)` conversion.

Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Methods inherited from interface org.springframework.cache.Cache
clear, evict, evictIfPresent, get, getName, getNativeCache, invalidate, put, putIfAbsent

- Constructor Detail
  - AbstractValueAdaptingCache
```
protected AbstractValueAdaptingCache(boolean allowNullValues)
```
    Create an AbstractValueAdaptingCache with the given setting.
    Parameters:
    allowNullValues - whether to allow for null values
- Method Detail
  - isAllowNullValues
```
public final boolean isAllowNullValues()
```
    Return whether null values are allowed in this cache.
  - get
```
@Nullable
public Cache.ValueWrapper get(Object key)
```
    Description copied from interface: Cache
    Return the value to which this cache maps the specified key.
    Returns null if the cache contains no mapping for this key; otherwise, the cached value (which may be null itself) will be returned in a Cache.ValueWrapper.
    Specified by:
    get in interface Cache
    Parameters:
    key - the key whose associated value is to be returned
    Returns:
    the value to which this cache maps the specified key, contained within a Cache.ValueWrapper which may also hold a cached null value. A straight null being returned means that the cache contains no mapping for this key.
    See Also:
    Cache.get(Object, Class), Cache.get(Object, Callable)
  - get
```
@Nullable
public <T> T get(Object key,
                 @Nullable
                 Class<T> type)
```
    Description copied from interface: Cache
    Return the value to which this cache maps the specified key, generically specifying a type that return value will be cast to.
    Note: This variant of get does not allow for differentiating between a cached null value and no cache entry found at all. Use the standard Cache.get(Object) variant for that purpose instead.
    Specified by:
    get in interface Cache
    Parameters:
    key - the key whose associated value is to be returned
    type - the required type of the returned value (may be null to bypass a type check; in case of a null value found in the cache, the specified type is irrelevant)
    Returns:
    the value to which this cache maps the specified key (which may be null itself), or also null if the cache contains no mapping for this key
    See Also:
    Cache.get(Object)
  - lookup
```
@Nullable
protected abstract Object lookup(Object key)
```
    Perform an actual lookup in the underlying store.
    Parameters:
    key - the key whose associated value is to be returned
    Returns:
    the raw store value for the key, or null if none
  - fromStoreValue
```
@Nullable
protected Object fromStoreValue(@Nullable
                                Object storeValue)
```
    Convert the given value from the internal store to a user value returned from the get method (adapting null).
    Parameters:
    storeValue - the store value
    Returns:
    the value to return to the user
  - toStoreValue
```
protected Object toStoreValue(@Nullable
                              Object userValue)
```
    Convert the given user value, as passed into the put method, to a value in the internal store (adapting null).
    Parameters:
    userValue - the given user value
    Returns:
    the value to store
  - toValueWrapper
```
@Nullable
protected Cache.ValueWrapper toValueWrapper(@Nullable
                                            Object storeValue)
```
    Wrap the given store value with a SimpleValueWrapper, also going through fromStoreValue(java.lang.Object) conversion. Useful for get(Object) and Cache.putIfAbsent(Object, Object) implementations.
    Parameters:
    storeValue - the original value
    Returns:
    the wrapped value

Class AbstractValueAdaptingCache

Nested Class Summary

Nested classes/interfaces inherited from interface org.springframework.cache.Cache

Constructor Summary

Method Summary

Methods inherited from class java.lang.Object

Methods inherited from interface org.springframework.cache.Cache

Constructor Detail

AbstractValueAdaptingCache

Method Detail

isAllowNullValues

get

get

lookup

fromStoreValue

toStoreValue

toValueWrapper